Target Organs for Lymphatic and Hematopoietic Cancers 

Comments/Suggestions by K. F. Eckerman 

Introduction 

The lymphatic system consists of bone marrow, spleen, tonsils, nodes, and thymus. The 

only nodes explicitly addressed in dosimetric models are those associated with the 

respiratory system in the head (ET) and thorax (TH). The number of nodes in the body 

has been indicated to be between 600 – 700; 8-37 in the arm pits, at least 50-60 in the 

lung, and 200-500 in the mesentery (ICRP 1975). The same mass has been estimated for 

the extrathoracic lymph nodes [LN(ET)] and thoracic lymph nodes (LN(TH)} in adults; 

the value being 12 and 15 g in the female and male, respectively (ICRP 1994). If the 60 

nodes in the lung have a mass of 15 g then the mass of the 600 nodes of the body would 

be 150 g. ICRP publications do not indicate a mass for the body’s lymph nodes. 

General Comment 

The following statement appears frequently in the proposed technical information 

bulletin. 

Due to the insoluble nature of many of the radionuclides ...the dose to the 

extrathoracic lymph nodes [LN(ET)] is typically higher than the dose to HNMO. 

While the statement is true, the thoracic lymph nodes [LN(TH)] are generally more 

highly irradiated that the extrathoracic nodes at least in ICRP’s calculations. This is 

typically the case for in most radionuclides of U, Th, Pu, Am, and Cm. Apparently 

IMBA differs for the standard calculations on this matter? (Note to Reader: The IMBA 

model does not differ from the standard ICRP model in this regard. The difference 

noted by Dr. Eckerman was due to an interpretation error by NIOSH)) Furthermore 

the LN(TH) are present in the thoracic not LN(ET) as apparently assumed here. 

Specific Comments: 

Table 1: ICD 200 – 200.18 

Below are my suggested changes by ICD for the internal – all externals accepted. 

a. 200.00 LN(TH) 

b. 200.01 LN(ET) 

c. 200.02 LN(TH) 

d. 200.04 LN(TH) 

e. 200.05 Colon 

f. 200.06 Colon 

g. 200.08 LN(TH) 

h. 200.10 LN(TH) 

i. 200.11 LN(ET) 

j. 200.12 LN(TH) 

k. 200.14 LN(TH) 

l. 200.15 Colon 

m. 200.16 Colon 
n. 200.18 LN(TH) 

Table 2: ICD 200.2-200.28 

Change all the internals target organs to LN(TH). Note the last sentence of the discussion 

following the table suggest that a large fraction of the lymph mass is in the thorax and yet 

the extrathoracic lymph was cited in the table. From the introduction the thoracic lymph 

as probably only about 1/10 of the total lymph node mass. 

Table 3: ICRP 200.8 – 200.08 

Below are my suggested changes by ICD for the internal – all externals accepted. 

a. 200.8 LN(TH) 

b. 200.80 LN(TH) 

c. 200.81 LN(ET) 

d. 200.82 LN(TH) 

e. 200.84 LN(TH) 

f. 200.85 Colon 

g. 200.86 Colon 

h. 200.88 LN(TH) 

Here again the discussion following the table associated LN(ET) with the thorax! Also 

the statement that the HNMO is the “claimant-favorable choice” is not clear since it rules 

out a metabolic organ. For insoluble materials the target of 200.85 and 200.86 is 

suggested above to be the colon rather than HNMO. Maybe these should be HNMO or 

Colon to be claimant favorable. 

Table 4: ICD 201-201.98 

Below are my suggested changes by ICD for the internal – all externals accepted. 

a. 201 LN(TH) 

b. 201.0 LN(TH) 

c. 201.00 LN(TH) 

d. 201.01 LN(ET) 

e. 201.02 LN(TH) 

f. 201.04 LN(TH) 

g. 201.05 Colon 

h. 201.06 Colon 

i. 201.08 LN(TH) 

j. 201.1 LN(TH) 

k. 201.10 LN(TH) 

l. 201.11 LN(ET) 

m. 201.12 LN(TH) 

n. 201.14 LN(TH) 

o. 201.15 Colon 

p. 201.16 Colon 

q. 201.18 LN(TH) 

r. 201.2 LN(TH) 

s. 201.20 LN(TH) 

t. 201.21 LN(ET) 
u. 201.22 LN(TH) 

v. 201.24 LN(TH) 

w. 201.25 (Colon) 

x. 201.26 (Colon) 

y. 201.28 LN(Th) 

z. 201.4 LN(TH) 

aa. 201.40 LN(TH) 

bb. 201.41 LN(ET) 

cc. 201.42 LN(TH) 

dd. 201.44 LN(TH) 

ee. 201.45 Colon 

ff. 201.46 Colon 

gg. 201.48 LN(TH) 

hh. 201.5 LN(TH) 

ii. 201.50 LN(TH) 

jj. 201.51 LN(ET) 

kk. 201.52 LN(TH) 

ll. 201.54 LN(TH) 

mm. 201.55 Colon 

nn. 201.56 Colon 

oo. 201.58 LN(TH) 

pp. 201.6 LN(TH) 

qq. 201.60 LN(TH) 

rr. 201.61 LN(ET) 

ss. 201.62 LN(TH) 

tt. 201.64 LN(TH) 

uu. 201.65 Colon 

vv. 201.66 Colon 

ww. 210.68 LN(TH) 

xx. 201.70 LN(TH) 

yy. 201.71 LN(ET) 

zz. 201.72 LN(TH) 

aaa. 201.74 LN(TH) 

bbb. 201.75 Colon 

ccc. 201.76 Colon 

ddd. 201.78 LN(TH) 

eee. 201.9 LN(TH) 

fff. 201.90 LN(TH) 

ggg. 201.91 LN(ET) 

hhh. 201.92 LN(TH) 

iii. 201.94 LN(TH) 

jjj. 201.95 Colon 

kkk. 201.96 Colon 

lll. 201.98 LN(TH) 

Table 5: ICD 202-202.08 
Change all internal target organs to LN(TH). Externals look OK. 

Table 6: ICD 202.1 – 202.18 

Use skin for the internal targets since it is explicit in the calculations. 

Table 7: ICD 202.2 – 202.28 

Same treatment as in Table 6 is suggested. 

Table 8: ICD 202.3- 202.38 

Since these cancers are found in connective tissue, which is a component of all solid 

organs, why not use the highest dose to a solid organ as the estimate for internal 

exposure. I would exclude bone surface from this list. 

Table 9: ICD 202.4 – 202.48 

OK 

Table 10: ICD 202.5-202.58 

Same comment at for Table 6 and 7. 

Table 11: ICD 202.6-202.68 

a. 202.6 LN(TH) 

b. 202.60 LN(TH) 

c. 202.61 LN(ET) 

d. 202.62 LN(TH) 

e. 202.64 LN(TH) 

f. 202.65 Colon 

g. 202.66 Colon 

h. 202.68 LN(TH) 

Table 11: ICD 202.8 – 202.98 

Change all internal targets to LN(TH). 

Table 13: ICD 203-203.01 

OK 

Table 14: ICD 203.1 -208.91 

OK 

References 

ICRP 1975. Report of the Task Group on Reference Man. ICRP Publication 23, 

Pergamon Press, Oxford UK. 

ICRP 1994. Human respiratory tract model for radiological protection. ICRP Publication 

66, Ann. ICRP 24(1-3).